ATR 42/72 AGEING PROGRAM FINALISED TO THE AIRFRAME LIFE EXTENSION

摘要

Ageing of structures has been deeply investigated and acknowledged as the main reason for certain accidents that happened in the late eighties. Main damage sources are the corrosion and the fatigue; both phenomena interact one against each other as mutual accelerating factors. To face this problem both the Federal Aviation Agency (FAA) and the Joint Aviation Authority (JAA) have established requirements for the continued airworthiness. Since ATR aircraft conform to modern design criteria regarding the damage tolerance, and their maintenance recommendations have been achieved on the basis of the MSG-3 analysis, a Life Extension of 50% (from 70,000 to 105,000 flights) was negotiated with the Airworthiness Authorities once satisfactory achieved the end of the Ageing Program. This paper describes the activity developed, since September 2002, to face the Ageing problem of the ATR Aircraft Primary Structure because the ATR fleet is approaching the end of their Economic Repair Life of 70,000 flights (The Fleet Leader Aircraft has achieved about 55,000 Flights). The Ageing Activity is based on the development of the followings five programs: Corrosion Prevention Control Programme (CPCP), Service Bulletin Review Program, Airworthiness Limitation Items Review Program, Repair Assessment Program (RAP) and Widespread Fatigue Damage Evaluation Program (WFD). Due to their impact on the Continued Airworthiness, a certain emphasis is put on the discussion of the RAP and on the WFD assessment activities.